Calculation and design of the heating furnace for straightening experimental samples of ship shafts

During operation the shafts of responsible purpose, which have received a curvature of the longitudinal axis and are not allowed for further operation, are subjected to correction with heating. The following heating methods are considered: with the use of a gas burner, induction heating, as well as tubular resistance furnaces. The use of a gas burner causes difficulties in the heating process controlling and the appearance of defects due to uneven heating afterwards. The diagram of the device for heating the shaft with a gas burner is illustrated. The scheme of induction heating of the shaft section is considered. During induction heating, it is necessary to use special equipment. It is proposed to use a tubular resistance furnace in an experimental study. The requirements for the material of the heating element are considered. A wire made of chromium-nickel alloy nichrome H20N80 for the heating element was selected. The layout of the tubular resistance furnace was made and materials were selected. The design of a resistance furnace for insulated windings is presented. Calculations of the length, diameter and number of turns of the heating element are performed. After manufacturing, a test heating of the sample was carried out. It is concluded that the furnace power was sufficient to warm up the sample to the required temperature of 650 °C for three hours.